The present invention relates to an arrangement for loading a deflection compensated roll or other elongated member in a paper/board or finishing machine and for providing an articulation bearing assembly, said roll or elongated member being provided with a stationary support shaft extending axially of the roll or the elongated member or with stub shafts present at the ends thereof, the support shaft ends or said stub shafts protruding from the roll or the elongated member and being mounted on a bearing block.
The present invention relates particularly to a deflection compensated zonewise controlled roll for use in various positions of a paper or board machine, such as a press section or a calender section, comprising a stationary support shaft mounted on frame structures through the intermediary of bearing blocks fitted with articulation bearings, and a shell mounted with bearings on the support shaft and rotating around the shaft and having a fixed position relative to the support shaft. The shaft is provided with hydraulic loading elements which are grouped in zones of one or more loading elements. A nip force is transmitted through the shell to the loading elements, and further to frame structures by way of the support shaft. The nip force distribution can be modified by adjusting the oil pressure applied to the loading elements of each zone. This type of deflection compensated roll is used with a counter roll to establish a nip, the loading of which is accomplished for example by loading the counter roll by means of separate hydraulic cylinders towards the relevant deflection compensated roll or e.g. by lifting the deflection compensated roll from its bearing blocks against the counter roll. Shifting the nip load onto the support shaft of a roll results in a deflection of the shaft and, hence, in a tilting of its ends, the compensation of which is effected by means of an articulation bearing present in a bearing block. In addition, the articulation bearing assembly allows an axial movement for the support shaft, e.g. such as results from heat expansion.
U.S. Pat. No. 3,802,044 to Spillmann et al., discloses pressure elements for a deflection compensated roll having a hollow cylindrical rotatable shell and a stationary shaft which extends through the shell and is supported at both its ends. The pressure elements are intended for maintaining the nip between the roll and a counter roll straight. The swivelling construction of the pressure element helps to maintain the element in the correct position against the shell, and to prevent its tilting with the roll shaft when the shaft bends under high pressure. The pressure elements of the Spillmann et al. patent do not load the roll against the counter roll, nor do they open or close the nip. This can be seen from the fact that the shell, which rotates around the stationary shaft, is mounted at both ends in bearings on the shaft. These bearings do not allow movement of the shell relative to the shaft, that is, the position of the shell relative to the counter roll can not be adjusted by means of the pressure elements. The pressure elements can only straighten the nip. The actual nip functionsxe2x80x94closing, loading, openingxe2x80x94are carried out by means of external devices, which are not shown in the Spillmann et al. patent. An exemplary external device in a loading arm provided with a hydraulic cylinder, by means of which the roll with its shaft is moved towards the counter roll or away from it. This type of solution is bulky and requires that the pair of rolls is mounted on a separate frame.
In the present invention, the main object is to combine an articulation bearing with the loading of a roll against a counter roll. This is achieved by arranging a hydraulic element in a bearing block, by means of which element the roll is loaded against the counter roll. Due to its construction, the element allows deflection of the roll shaft. The solution of the present invention makes it possible to dispense with external loading elements, such as loading arms. Therefore, the solution entails substantial space saving as it is possible to bind together the pair of rolls through their bearing housings, that is, it is possible to obtain a pair of rolls without a separate frame structure.
It is one object of the present invention to provide an arrangement, whereby a deflection compensated roll or other elongated member, such as e.g. a doctor bar or a curved roll, can be loaded and fitted with articulation bearings in a relatively simple fashion. In order to accomplish this object, an arrangement of the invention is characterized in that the arrangement comprises at least one hydrostatically journalled or hydraulically relieving main loading element, which is mounted on a bearing block and works on the support shaft or stub shaft of a roll or other elongated member and which constitutes a loading element and, at the same time, an articulation bearing assembly for the discussed roll or other elongated member.